Detection of antigens is important for many areas of scientific research, diagnostic use and therapeutic uses. There are several ways in which antigens can be detected. Various methods are described in U.S. Pat. Nos. 5,160,701, 5,141,850, PCT Publication WO 91/12336, U.S. Pat. Nos. 5,451,504, 5,559,041, European Patent Application No.: 0505636A1, PCT Publication No. WO 88/08534, European Patent Application No. 0284 232A1, U.S. Patent Application Publication No. 20070020768 and U.S. Pat. No. RE39664, each of which is hereby incorporated by reference in its entirety. The methods and devices available prior to the present invention may still require improvements in sensitivity or speed at which results can be obtained. These factors can be important where time is of the essence when attempting to determine the presence or absence of an antigen.
One such area is the area of detecting food borne pathogenic contaminants. Approximately, seventy-six million people in the United States become afflicted with a food borne illness. Of those seventy-six million, approximately, 325,000 will become violently ill, requiring hospitalization, and approximately 5,000 will die. The majority of food-borne illnesses are causes by Salmonella, E. coli, and Campylobacter costing approximately $35 billion dollars.
Current measures at ensuring a safe food supply involve a combination of local, state and federal authorities as well as an elaborate system of inspectors and surveillance networks. Food manufacturers are held to certain United States Department of Agriculture, United States Food and Drug Administration, and the National Marine Fisheries Service regulations that are enforceable by law. The USDA has created a system of health inspectors that are charged with performing daily meat, produce, and other consumable products inspections made or processed in manufacturing and processing facilities. These inspections have been created to involve a detailed statistical analysis to best ensure safety and sterility of food before it reaches the consumer. Moreover, the majority of the meat industry has adopted irradiation techniques to further demonstrate sterility of products. At a lower level, local and municipal health departments work to ensure that local distributors, restaurants, and retailers follow strict guidelines to ensure a safe food supply. However, despite this elaborate network, food-borne infections are still common.
Once an outbreak is strongly suspected, an investigation begins. A search is made for more cases among persons who may have been exposed. The symptoms and time of onset and location of possible cases are determined, and a “case definition” is developed that describes these typical cases. The outbreak is systematically described by time, place, and person. A graph is drawn of the number of people who fell ill on each successive day to show pictorially when it occurred. Calculating the distribution of cases by age and sex shows whom is affected.
Often the causative microbe is not known, so samples of stool or blood must be collected from ill people and sent to the public health laboratory to make a diagnosis. Each collection and sampling can cost upwards of $500 per test and often takes 2-4 days for analysis (CDC “Food-borne Infections”).
Prior to the present invention, to identify the food or other source of the outbreak, the investigators first interview a few persons with the most typical cases about exposures they may have had in the few days before they got sick. In this way, certain potential exposures may be excluded while others that are mentioned repeatedly emerge as source possibilities. Combined with other information, such as likely sources for the specific microbe involved, hypotheses are then tested in a formal epidemiologic investigation. The investigators conduct systematic interviews about a list of possible exposures with the ill persons, and with a comparable group of people who are not ill. By comparing how often an exposure is reported by ill people and by well people, investigators can measure the association of the exposure with illness. Using probability statistics, the probability of no association is directly calculated.
As new food-borne problems emerge there is a need for novel devices and methods for detecting food borne pathogens. The present invention provides a device for the detection of antigens, such as antigens from food-borne bacteria, and fulfills the needs of having a device and assay with increased sensitivity and/or speed of detection. The present invention fulfills other needs as well as will be discussed herein.